C1736

CIRCUIT DESCRIPTION
The Electronic Leveling Control (ELC) compressor is switched ON and OFF via a compressor relay which is controlled by the CVRSS control module. The control module circuitry provides a switched path to ground (low-side drive) whenever compressor activity is required. This drive circuit is also continually monitored to determine if the voltage level agrees with the commanded state.

CONDITION FOR SETTING THE CODE "CURRENT"
The Continuously Variable Road Sensing Suspension (CVRSS) control module sees a low voltage at pin "C15" during a compressor OFF-state.

ACTIONS TAKEN WHEN CODE SETS
The ELC compressor relay output drive is disabled for the remainder of the ignition cycle.

CONDITION FOR CODE TURNING "HISTORY"
The CVRSS control module no longer senses a low voltage at pin "C15" when the compressor relay output drive is in an OFF-state.

HOW TO CLEAR THE CODE
^ Use the scan tool.
^ Use the On-Board diagnostic "CLEAR RSS CODES" feature.

TEST DESCRIPTION
The numbers below refer to step numbers on the diagnostic table.
2. Checks to see if the ignition fuse to the relay is blown.
3. Checks to see if ignition voltage is present.
4. Checks for an open in circuit 147.
5. Checks for an internal open in the relay coil.
6. Checks for an open in circuit 321.
7. Checks for an internal short in relay coil.
8. Checks for short to ground in circuit 147.
9. Checks for short to ground in circuit 321.

DIAGNOSTIC AIDS
This fault condition is detectable only when the compressor relay output is commanded to the OFF-state, which occurs whenever compressor activity is not required. The control module expects to see a high voltage during the OFF-state.

Only electrical problems with the compressor relay coil circuit are flagged. Compressor motor problems and pneumatic leakage problems do not set a code, but the CVRSS control module shuts the compressor relay off if there is no progress, or if excessive run times occur. Recovery is not attempted until ignition is cycled OFF and ON.